How are phages beneficial in Earth’s oceans?
The correct answer and explanation is:
Correct Answer:
Phages (bacteriophages) are beneficial in Earth’s oceans because they regulate bacterial populations and play a key role in nutrient cycling.
300-Word Explanation:
Phages, or bacteriophages, are viruses that infect and kill bacteria. In Earth’s oceans, they are incredibly abundant—there are an estimated 10³¹ phages globally, and many are found in marine environments. Their presence is crucial to maintaining the balance of life in the ocean.
One of the main benefits of phages is that they control bacterial populations. By infecting and lysing (breaking open) bacterial cells, phages prevent any one type of bacteria from growing unchecked. This regulation maintains microbial diversity, which is essential for a healthy and stable ocean ecosystem.
Another major benefit of marine phages is their role in nutrient cycling. When phages lyse bacterial cells, the contents of the cells—such as organic carbon, nitrogen, and phosphorus—are released into the surrounding water. This process, known as the “viral shunt,” redirects nutrients from larger organisms (like zooplankton or fish) back into the microbial loop. As a result, dissolved organic matter becomes available to other microorganisms, such as phytoplankton, which form the base of the marine food web and produce much of the planet’s oxygen through photosynthesis.
Phages also drive microbial evolution through horizontal gene transfer. As they infect different bacterial hosts, they can transfer useful genes between them. This process promotes genetic diversity and adaptability among marine bacteria, enabling them to respond more effectively to environmental changes.
Overall, phages are microscopic but mighty players in ocean ecosystems. They help maintain ecological balance, enhance nutrient recycling, and shape microbial evolution. Without phages, marine ecosystems would be less stable and less productive, and global biogeochemical cycles—including those involved in carbon and oxygen—would be profoundly affected.